多元低/非贵金属纳米晶的可控合成及催化液态化学储氢材料制氢研究

Hydrogen, producing only water as a byproduct, has emerged as one of the potential carbon-neutral energy carrier alternatives. Storage of hydrogen as a compressed gas is the current state-of-the-art, but to avoid the risk of high pressures and increase the storage density, numerous hydrogen storage approaches are currently under investigation. Among them, the liquid-phase hydrogen storage materials, which are easy to handle and transport (using the existing liquid-based fuel distribution infrastructure), without the involvement of any solid byproduct, have been considered more advantageous over the traditional solid-phase hydrogen storage materials. Formic acid and hydrous hydrazine have attracted considerable attentions as the safe and convenient hydrogen storage materials due to their high hydrogen contents, liquid at room temperature and easy recharging abilities. A number of noble metals and their alloys based nanocatalysts have been recently developed, however, low/non-noble metal containing nanocatalysts possessing prominent activity and selectivity at room temperature are still few. On the other hand, the development of an efficient synthetic strategy to obtain multi-metallic nanomaterials with a desirable structure on large scale is strongly required to clarify the structure-composition-property relationship of nanomaterials and to investigate their possible applications in catalysis. However, the controlled synthesis of nanocatalysts consisting of multiple metal components has been relatively unexplored in comparison to monometallic and bimetallic nanocatalysts. It is recognized that the capping agent, reaction solvent and reducing agent are of great importance for the synthesis of monodisperse nanoparticles (NPs). Recently, amine-boranes, the classical Lewis acid-base adducts, have been employed as reducing agents for the synthesis of metal NPs. They offer much better control in reducing rate and, hence, the particles size distribution of metal NPs over the traditional reducing agents like borohydrides. Moreover, the reducing abilities of the amine-boranes could be controlled by varying the substituents on the nitrogen or boron atom. However, the effect of different amine-boranes on the morphology of nanomaterials, to the best of our knowledge, has been rarely explored. In this project, we will develop an efficient way of using amine-boranes as the reducing agents in morphology-controlled synthesis of multi-metallic monodisperse nanocatalysts, and study their applications as efficient catalysts toward hydrogen generation from liquid chemical hydrogen storage materials (formic acid and hydrous hydrazine).

氢气的安全存储和运输一直是制约“氢能经济”发展的瓶颈。相比于固体储氢材料，液态储氢技术具有储氢量大，存储、运输方便，便于利用现有的储油和运输设备等优点，更受到人们的关注。其中，甲酸和水合肼由于脱氢产物的再生可以通过各种有效的方法实现，它们在室温下选择性脱氢成为目前研究的难点。然而，目前高效的催化剂仍然是以贵金属为主。另一方面，在纳米催化剂的合成上，相比于传统的还原剂硼氢化物，氨基硼烷具有更弱的还原性，其还原性可以通过氨基硼烷的类型进行调控，可以通过对还原速率的调控，影响纳米晶的尺寸、形貌和催化性能等。氨基硼烷作为固体化学储氢材料被广泛研究，但是，作为还原剂，对金属纳米晶的可控合成研究不多。本项目计划通过对还原剂氨基硼烷结构的调控，实现对多元低/非贵金属单分散纳米晶的可控合成，找到纳米晶的组成、尺寸、形貌、暴露晶面等与氨基硼烷结构之间的联系，并研究它们在催化甲酸和水合肼分解制氢上的应用。

氢气的安全存储和运输一直是制约“氢能经济”发展的瓶颈，发展高效的液态储氢技术是目前研究的热点和难点。在本项目的资助下，成功合成了N取代、B取代和N、B共同取代的氨基硼烷衍生物，由于其独特的结构和高储氢量，这些氨基硼烷衍生物又可以作为非常有潜力液态化学储氢材料。同时，探究了此类氨基硼烷作还原剂，在金属纳米晶的合成中对其化学组成和尺寸的调控以及催化性能的影响。合成了一批具有高催化活性的高选择性的纳米催化剂在室温下催化甲酸和水合肼分解制氢。另外，在项目的资助下，围绕与氢能经济相关的电解水产氢和燃料电池做了一些初步的研究。